Method or process of making leather-board.



UNITED STATES PATENT OFFICE.

ALBERT'L. GLAPI, OF BRAINTREE, MASSACHUSETTS, ASSIGNOR TO HIDE-ITELEATHER COMPANY, OF BOSTON, 'MASSACHUSETTS, A CORPORATION OF MAINE.v

METHOD OR PROCESS OF MAKING LEATHER-BOARD.

No Drawing.

State of Massachusetts, have invented cer-' tain new and. useful Improvements 1n Methods or Processes of Making Leather- Board, of which the following is a specification. Y,

My present invention pertains to an improved method of making leatherboard, the main objects being to remove tannic acid from the stock before the addition of the material employed to waterproof it, whereby the waterproofing operation is facilitated and the character of the product improved; to conserve such removed tannic acid and other materials that may be in solution; and to utilize such removed material in the manufacture of the leatherboard.

In the production of waterproof leatherboard it is necessary in order to insure a homogeneous and thoroughly waterproof board that the stock should be thoroughly and'evenly, Waterproofed throughout, and it is likewise desirable that the board should contain all the constituent elements of the leather scrap from Which the board is formed. In processes of waterproofing the stock in which a substance such as a soap compound or emulsion, or a solution of casein or glue, is mixed with the stock and then subjected to the action of a precipitant in order to deposit upon the fiber of the stock an insoluble compound to waterproof the same, the presence of tannic acid tends to impede proper action, and to cause the waterproofing material to coagulate or ourdle, which, of course, is fatal to proper distribution of the material evenly and thoroughly in and through the stock; and the removal of the tannic acid renders the fibers of the stock more receptive to the waterproofing material.

It has heretofore been proposed to remove the free tannic acid, or some portion of it, by washing the stock in Water. As this process has been carried on, however, the wash Water has been run to Waste, and there has been a waste of the water-soluble ingredients of the leather stock, such ingredients passing off with the Wash water.

My present invention consists in a method by which such ingredients may be utilized in the process andconserved in the product.

waterproofing material.

Specification of Letters Patent. Patented Feb. 16 19} 5 Application filed January 11, 1913. Serial N 0. 741,477. 7

After washing'the charge of stock, which, as will be understood, is produced from leather-scrap, the wash water, having been drained oil or removedin a suitable mannor is conveyed to a storage tank, and after deposited upon the fibers of the stock. Since the tannic acid contained in the wash water from any one charge'will hardly be suiticient to cause a precipitation of suflicient waterproofing material for the stock, it will 1n most cases be desirable to add to the water containing the tannic acid alum or some other suitable precipitant in quantities sufiicient to complete the precipitation of the The amount of alum, if any, necessary to be added in order to accomplish the complete precipitation will depend 011 the quantity of tannic acid which is present in the water and can read- 11y be determined by analysis. It is also desirable to add alum to the water on account of the presence in the Water of soluble organic matters in addition to the tannic acid, which matters are insoluble in the presence of alum, and will therefore be Precipi- I tated when the alum is added to the water, thus becoming capable of retention in the finished product. The precipitation of these other organic matters in facilitated by heating the water to a temperature above the coagulation point of albumen, say 180 F.

If the water is heated, it should, of course,

vbe allowed to cool again before being re-' stored to the beater engine.

Having thus described my invention,

removing the Wash water, mixing with the stock a Waterproofing material capableof depositing on the fibers thereof by a reaction with tannic acid an insoluble precipitate, and thereafter adding to the mixture the 'tannic acid contained in the wash water.

3. In the manufacture of leatherboard, the process of washing that portion of the stock consisting of leather scrap or fibers,

removing the wash water, mixing with the stock a waterproofing material capable of depositing on the fibers thereof by a reaction with tannic acid an insoluble precipitate, and thereafter using the tannic acid contained in the wash water as a precipitant to react on the'water'proofing material.

4. In' the manufacture of leatherboard,

the process of washing that portion of the stock consisting of leather'scrap or fibers, removing the wash water, mixing with the stock a waterproofing material capable of In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

ALBERT L. CLAPP. Witnesses:

Homes A. Donen, BENNETT S. Jonas. 

